Current standards are set by the American Lumber Standard Committee, appointed by the Secretary of Commerce.ĭesign values for most species and grades of visually graded structural products are determined in accordance with ASTM standards, which consider the effect of strength reducing characteristics, load duration, safety and other influencing factors. These standards have changed over the years to meet the changing needs of manufacturers and distributors, with the goal of keeping lumber competitive with other construction products. The move to set national standards for lumber in the United States began with publication of the American Lumber Standard in 1924, which set specifications for lumber dimensions, grade, and moisture content it also developed inspection and accreditation programs. Therefore, they vary considerably in strength, utility and value. Individual pieces of lumber exhibit a wide range in quality and appearance with respect to knots, slope of grain, shakes and other natural characteristics.

Structural Wood Lumber Engineering Properties | Modulus of Elasticity of Wood | Wood Engineering Design Data.Structural Wood Lumber Engineering Properties 5' and Larger